Concluding and evaluating practice questions.

In forty club swimmers, weekly training hours and maximal oxygen uptake show a strong positive correlation. Which conclusion do these data support?

• Increasing weekly training hours would raise the maximal oxygen uptake of any group of swimmers
• The higher training volume caused the higher oxygen uptake values in these swimmers
• A swimmer's oxygen uptake determines the number of hours that swimmer chooses to train
• Training hours and oxygen uptake are positively associated in this sample

Answer: Training hours and oxygen uptake are positively associated in this sample

A correlation reports that two measured variables move together in this sample; the direction of the effect could be reversed and a third factor such as training history could drive both, so a causal claim needs a controlled intervention.

A heart rate monitor used throughout a step test reads 5 bpm above the true value at every intensity. What is the effect on the results?

• All recorded rates are too high by the same amount
• The repeats scatter more widely about a mean that is still correct
• Only the highest recorded rates in the test are affected
• The mean is unaffected because the error cancels out over the repeated trials

Answer: All recorded rates are too high by the same amount

A systematic error displaces every reading in the same direction by the same amount, so the mean is wrong but the spread is unchanged; averaging more trials cannot remove it, and only calibration against a known standard can.

Which statement is usable as an evaluation point about hand timing in a study of 30 m sprint performance?

• The stopwatch used in the study was not particularly accurate on the day of testing
• Starting the watch late made every recorded time too short
• There were several errors during the testing session
• The participants were not all of the same standard

Answer: Starting the watch late made every recorded time too short

An evaluation point names the source of the problem and the direction in which it moved the data, so the reader knows whether the true value is above or below the reported one; vague statements about accuracy or errors cannot be acted on.

An agility course gives almost identical times for the same players on three separate occasions, but the times do not distinguish the players the coaches rate as agile in matches. What does this indicate?

• The test is valid but not reliable
• The test is affected by a large random error on each occasion
• The test is reliable but not valid
• The test is neither reliable nor valid in this group of players

Answer: The test is reliable but not valid

Reliability is repeatability, validity is measuring the intended quality; a closed course run alone can be highly repeatable while missing the perception and decision making that agility in a match demands.

Participants complete an unfamiliar slalom dribbling course three times in one session and improve on every attempt. How should the first attempt be interpreted?

• It is the most valid measure because the participants were not yet fatigued
• The improvement is caused by a systematic error in the timing gates
• The three attempts should be averaged because the change is random variation
• It underestimates true performance because of a learning effect

Answer: It underestimates true performance because of a learning effect

On a novel task the early trials measure familiarity as much as ability, so the first attempt sits below the performer's real level; familiarisation trials before data collection are the standard control for this.

A study reports that six weeks of plyometric training raised mean jump height in fourteen netball players. Which extension addresses the main weakness of the design?

• Repeating the same testing session with the same players on the following day
• Adding a group that trains without the plyometric sessions
• Reporting the jump heights to one more decimal place than before
• Testing the same players once more at the end of the six-week programme

Answer: Adding a group that trains without the plyometric sessions

Without a comparison group any other training, maturation or familiarity with the jump mat could explain the gain; a control group tested at the same two time points isolates the effect of the plyometric sessions.